Hot-fillable plastic containers are designed for the packaging of liquids (e.g., juice) which must be placed in the container while hot to provide for adequate sterilization. During filling, the container is subjected to elevated temperatures on the order of 180.degree.-185.degree. F. (the product temperature) and positive internal pressures on the order of 2-5 psi (the filler fluid pressure). The container is then capped and as the product cools, a negative internal pressure is formed in the sealed container.
Biaxially-oriented polyethylene terephthalate (PET) beverage bottles have been designed to receive a hot-fill product with controlled thermal shrinkage and minimum distortion. Such a bottle is described in U.S. Pat. No. 4,863,046 entitled "Hot Fill Container," which issued Sep. 5, 1989 to Collette et al. The Collette container is provided with a plurality of recessed vacuum panels in the middle panel section of the container, which reduce the magnitude of the vacuum generated in the sealed container to prevent any large uncontrolled geometric distortion. As the product cools, the vacuum panels deform and move inwardly in unison. A wrap-around label covers the vacuum panels and is supported by raised central wall portions in the vacuum panels, post areas between the vacuum panels, and horizontal glue land areas above and below the vacuum panels. Vertical recessed ribs may be provided in the post areas and within the vacuum panels to increase the longitudinal stiffness of the panel section.
Pasteurization is another method of sterilization which subjects a container to elevated temperatures and internal pressures. In this case, the container is filled with a cold (room temperature or below) liquid product, which may or may not be carbonated, the container is sealed, and then the sealed container is sent through a pasteurization chamber where both the product and container are subjected to an elevated equilibrium temperature (i.e., up to about 70.degree.-75.degree. C.) for a period of time (e.g., ten minutes) in order to effect sterilization. This lengthy exposure period at elevated temperatures generates high internal pressures due to fluid vaporization. After pasteurization, the container must be cooled without undergoing significant distortion or vacuum collapse.
A need exists to provide a thermal-resistant container, such as a hot-fill or pasteurizable container, with a handle to facilitate carrying and controlled pouring. This is especially true with larger-sized containers, e.g., 64-oz, 128-oz and larger, as the weight of the product and size of the container make it difficult for the user to handle the same. An integral handle is difficult to form with strain-hardenable materials, such as polyester. A separately-formed handle requires a secure attachment mechanism, especially with larger-sized (i.e., heavier) containers. And as always, to be commercially successful, a handled container must be capable of being manufactured at the lowest possible cost, which usually means minimum cycle time on high-production manufacturing equipment and a minimum number of additional manufacturing steps.
Numerous attempts have been made to accomplish in-mold attachment of a handle to a plastic container in a commercially viable manner. However, most of these attempts have not been successful because in-mold handle attachment involves: (a) more complex blow-molding equipment to enable insertion of a pre-made handle into a container blow mold at the correct position; (b) the added time for inserting the handle into the mold, which slows down the blowmolder throughput; and (c) the difficulty in blow-molding a complex handle-attaching shape, due to the strain-hardening characteristics of polyesters and other plastics. Thus, in-mold handle attachment has significant drawbacks.
Another difficulty with providing handles for thermal-resistant containers (e.g., hot fill or pasteurizable), whether done in-mold or post-mold, is that the high-temperature exposure may distort the container and/or handle such that there is no longer a secure engagement of the handle and container. Thus, there have been few attempts to commercialize a thermal-resistant container having a separate handle, especially in larger-sized containers.
A large-size (128-oz) hot-fillable juice container with a bale handle, sold by Ocean Spray Company, of Lakeland, Mass., is shown in FIGS. 1-2. This stretch blow-molded PET container 2 has a cylindrical sidewall panel 3 with six vacuum panels 4 disposed symmetrically about the circumference, to alleviate vacuum collapse. Rather than attempting to attach a handle to the container sidewall (which sidewall is subjected to increased pressure, thermal shrinkage, and vacuum collapse during the hot-fill process), a bale-type handle 5 is snap fit over a flange 6 adjacent the neck finish 7. The polyethylene handle 5 includes a ring portion 8 which can be stretched to enable its insertion over the neck flange 6 and subsequent release so as to be maintained under the flange. An extending "U"-shaped member 9 extends from the ring which is intended to be grasped by one hand of the user during carrying and pouring. It is necessary to use two hands during pouring, one attached to the bale and the other for lifting the base of the container. It is somewhat difficult to pour from this container into small cups, due to the large size and weight of the container. A small cup must normally be brought up close to the container opening 10, to prevent spillage. This difficulty with controlled pouring into small cups is partly due to the large container opening at the neck finish, which is necessitated by the stretch blow molding characteristics of polyethylene terephthalate (PET), i.e., in order to achieve the necessary level of axial and hoop expansion in the container, a preform having a relatively large opening is required for making this large-volume container. Thus, the present commercial hot-fillable container with a bale handle has a number of limitations.